package com.yupi.springbootinit.utils;

import cn.hutool.core.collection.CollUtil;
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.support.ExcelTypeEnum;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ObjectUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.util.ResourceUtils;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
@Slf4j
public class ExcelUtils {

    /*
    * excel 转csv
    * */

    public static String excelToCsv(MultipartFile multipartFile)  {
//        File file =null;
//        try {
//            file=ResourceUtils.getFile("classpath:网络传输.xlsx");
//        } catch (FileNotFoundException e) {
//            e.printStackTrace();
//        }
        //读取数据
        List<Map<Integer, String>> list = null;
        try {
            list = EasyExcel.read(multipartFile.getInputStream())//拿到输入流
                    .excelType(ExcelTypeEnum.XLSX)
                    .sheet()
                    .headRowNumber(0)
                    .doReadSync();
        } catch (IOException e) {
            log.error("转换csv错误");
        }
        if (CollUtil.isEmpty(list)){
            return "";
        }
        StringBuilder stringBuilder =new StringBuilder();
        //有序map，读取表头
        LinkedHashMap<Integer, String> headerMap = (LinkedHashMap)list.get(0);
        List<String> headerList = headerMap.values().stream().filter(ObjectUtils::isNotEmpty).collect(Collectors.toList());
        stringBuilder.append(StringUtils.join(headerList,",")).append("\n");
        //读取数据
        for (int i = 1; i < list.size(); i++) {
            LinkedHashMap<Integer, String> dateMap = (LinkedHashMap)list.get(i);
            List<String> dataList = dateMap.values().stream().filter(ObjectUtils::isNotEmpty).collect(Collectors.toList());
            stringBuilder.append(StringUtils.join(dataList,",")).append("\n");
        }

        //转csv

        return stringBuilder.toString();
    }

    public static void main(String[] args) {
        excelToCsv(null);
    }
}
